Just a day after astronomers warned that a near-Earth asteroid had a small chance of colliding with the Earth in 2030, new data released Saturday ruled out an impact but raised the possibility that the body could pose a threat to the Earth in the future.

The new data came in the form of "pre-discovery" observations made in May of this year by the Catalina Sky Survey in Arizona, four months before University of Hawaii astronomers discovered asteroid 2000 SG 344. The observations were re-analyzed on Friday after the International Astronomical Union (IAU) announced that the asteroid had a one-in-500 chance of colliding with Earth in September 2030.

Those observations allowed astronomers to refine the asteroids orbit and more accurately determine its position in the future. The new orbit shows that the asteroid will pass no closer to Earth than 2.7 million miles (4.3 million kilometers), or 11 times the distance of the Moon, in 2030, thus eliminating any possibility of an impact.

The new observations do not shed any light on the nature of the asteroid, however. Based on its brightness astronomers estimate it is 100 to 230 feet (30 to 70 meters) in diameter. However, its unusual orbit leads astronomers to speculate that it could be the spent upper stage of a rocket booster dating back to the Apollo era.

While 2000 SG 344 poses no risk to Earth in 2030, astronomers have not ruled out the possibility that it could collide with Earth later in the 21^st century. "While the new orbital calculations have ruled out the 2030 event, they have also increased the likelihood of encounters in years after 2030," Don Yeomans, manager of NASAs Near-Earth Object office, said in a statement Saturday. "For example, for the date September 16, 2071, current computations indicate roughly a one-in-1,000 chance of an Earth impact."

Fridays announcement of the possible impact of 2000 SG 344 based on limited data -- and the rapid retraction of that threat -- may generate controversy among astronomers still smarting from the 1997 XF 11 asteroid scandal of 1998. In March 1998, astronomers said that asteroid had a small chance of colliding with Earth in 2028. Additional data released a day later eliminated the threat. That episode led the creation of new guidelines by the IAU for reporting impact threats that were followed for 2000 SG 344.